Paleontologists in Australia have unearthed the fossilized skull of Genyornis newtoni, a species of giant flightless ‘mihirung’ that became extinct around 45,000 years ago.
The illustration portrays a reconstruction of Genyornis newtoni at the water’s edge in a wetland or swamp-like environment. The scene itself was inspired by locations that exist in southern South Australia today, such as Ngarrindjeri country in and around the Coorong and lower Murray River. However, back when Genyornis newtoni was kicking about, this type of environment would have been more widespread across the country. Many Genyornis fossils are recovered from Lake Callabonna which is more than a day’s drive north of there and is a dry salt lake nowadays. Back in the day this would have been much wetter place. Image credit: Jacob C. Blokland.
Genyornis newtoni belongs to Dromornithidae (mihirungs), an extinct clade of flightless Australian birds of the Oligocene through Pleistocene epochs.
Also known as the Newton’s mihirung, the species lived in Australia until 48,000-45,000 years ago.
The bird stood over 2 m tall, weighed between 220-240 kg, had tiny wings and massive hind legs, and laid melon-sized eggs of around 1.5 kg.
The only previously known skull for this species, reported on in 1913, was heavily damaged and with little of the original bone remaining, not much could be deduced about the skull of this species.
The new, well-preserved specimen was found in the saline, dry beds of Lake Callabonna, a remote region of inland South Australia.
As expected from such a giant bird, the skull was far from ordinary, with massive braincase, large upper and lower jaws, an unusual casque on the top of it head.
The upper beak especially, showed surprising morphology, differentiating this bird from even its closest relatives, which are otherwise fairly similar.
“Genyornis newtoni had a tall and mobile upper jaw like that of a parrot but shaped like a goose, a wide gape, strong bite force, and the ability to crush soft plants and fruit on the roof of their mouth,” said Dr. Phoebe McInerney of Flinders University.
“Aspects of the skull also showed undeniable and complex similarities to that of early diverging waterfowl lineages, the South American screamers and, a bit closer to home, the Australian magpie goose.”
“The exact relationships of Genyornis within this group have been complicated to unravel, however, with this new skull we have started to piece together the puzzle which shows, simply put, this species to be a giant goose.”
“We were particularly excited to discover the first fossil upper bill of Genyornis, for the first time we could put a face on this bird, one very different to any other bird, yet like a goose,” said Dr. Trevor Worthy, also from Flinders University.
The skull of Genyornis newtoni. Image credit: McInerney et al., doi: 10.1080/08912963.2024.2308212.
Assessing the morphology of the skull also provided researchers with an in-depth view of how the head would have functioned by making an assessment on the muscles and available movement in each of the joints.
“The form of a bone, and structures on it, are partly related to the soft tissues that interact with them, such as muscles and ligaments, and their attachment sites or passages,” said Flinders University researcher Jacob Blokland.
“Using modern birds as comparatives, we are able to put flesh back on the fossils and bring them back to life.”
In addition, the paleontologists found Genyornis newtoni had several unusual adaptations for aquatic habitats, allowing for the protection of their ears and throat from an influx of water when the head is submerged.
These adaptations further support the species being no other than a giant prehistoric goose and are potentially linked to its extinction as fresh water bodies in northern South Australia are now mostly salt lakes.
“With this skull, we now know so much more about Genyornis newtoni than ever before, having gained a greater understanding of these birds which once broadly roamed the Australian outback and their ultimate disappearance,” the researchers concluded.
Their paper was published in the journal Historical Biology.
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Phoebe L. McInerney et al. Skull morphology of the enigmatic Genyornis newtoni Stirling and Zeitz, 1896 (Aves, Dromornithidae), with implications for functional morphology, ecology, and evolution in the context of Galloanserae. Historical Biology, published online June 3, 2024; doi: 10.1080/08912963.2024.2308212
Source : Breaking Science News